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12

Gluconeogenesis is not the reversal of the glycolysis, but the generation of glucose from non-carbohydrate precursors (like odd chain fatty acids and proteins). The reason why we have this process is because some organs and tissues can only use glucose as their energy source. These include the brain (although ketone bodies can be used here as well), ...


8

High intracellular glucose. Affects: all cells that do not depend on insulin to take in glucose. Examples: neurons [1], kidney cells, retina cells. Causes: high extracellular glucose (in most cases hyperglycemia) Effects: promoting necrotic cell death through $H_2O_2$ (peroxide) formation, which may participate in the development of diabetic ...


8

The minimum requirement for E. coli and other bacteria to grow and survive is called minimal medium. It's even defined at Merriam-Webster: a medium that contains only inorganic salts, a simple carbon source (as carbon dioxide or glucose), and water Water and glucose are pretty easy, but the source of salts may often change; regardless, you really need ...


7

Human body is a glucose driven machine which intake carbohydrates and converts to glucose. Energy is yielded from the glucose and glucose is stored as glycogen. When the carbohydrate intake is somehow reduced then body will shift its mechanism and uses the fatty acids to produce energy. Liver synthesis ketones from fatty acids in our diet or from body fat. ...


7

This condition is also known as "lactic acidosis" and can be pretty dangerous, since it influences the pH of the blood. When we metabolize glucose to produce ATP and NADH it is metabolized finally to pyruvate in a process called glyolysis (I am not going into detail here since this is nicely explained in the Wikipedia). Pyruvate can then be used further in ...


7

Is the standard Lotka-Volterra (LV) model an exact fit for insulin-glucose (IG) dynamics? No. Can a similar model built on the same principles capture most of the essential features of the IG dynamics? Absolutely. How to capture most of the insulin-glucose dynamics using a slightly modified Lotka-Volterra model We can figure out how to change the LV ...


7

The question is a bit unclear, it should be reframed as suggested by AliceD. To simply answer the question, Glucose is the substrate, and in the first step it is converted to Glucose-6-phosphate. Only the Phosphate group is added which originates from ATP, your notes also are a bit misleading because it tends to suggest that Hydrogen is released, which is ...


7

In short, sugars are absorbed quicker than proteins and fats because they pass through the stomach quicker and their digestion is simpler. Sugar can be absorbed through the mouth mucosa when applied as a sublingual gel, as discussed here on Biology SE: Is sugar absorbed into the bloodstream through the walls of the mouth?, but probably in much smaller ...


6

Glucagon and cortisol are VERY different types of hormones, though each of them can affect glucose metabolism and effectively can increase glucose concentrations in the blood (albeit through different mechanisms). Glucagon, pictured above, is a 31 amino acid peptide hormone (i.e. PROTEIN) that is released from the alpha-cells within the pancreatic islets. ...


6

Avoiding diffusion is one reason to phosphorylate glucose, the other is that it is removed from the osmotic balance between inside and outside of the membrane, so it can be transported at a high rate. The Glucose-6-phosphate can then be used as a substrate for different pathways, namely glycolysis and the pentose phosphate way, and (depending on the ...


5

Short answer Facilitated diffusion is a passive process in which membrane channels mediate the transport of polar, or big molecules that are not solvable in the cell membrane. Co-transport, on the other hand, is active transport, as it depends on the electrochemical gradient of ions across the cell's membrane, particularly Na+. Because ATP or other energetic ...


5

Nice question. Beginning with Krebs cycle, there is actually no specific answer as both GTP and ATP are produced. First, see this article for why GTP is the more frequent product: It may be that at the beginning, both GTP and ATP were equally available for energy and that the succinyl CoA synthetase reaction happened to choose GTP and that reaction is ...


4

Yes, but no. In other words, this quote is not probably not true in the ways you'd think. Bacteria can survive on practically nothing for long periods of time, but whether you call that life is subjective. Nitrogen is necessary for all the co-enzymes and proteins to sustain life. In order to get energy, if E coli. needs to metabolize nitrogen to waste at ...


3

In prokaryotes the glucose transporter is always present in the cell membrane; in cells whose glucose uptake is insulin-regulated the transporter is only present in the plama membrane when hormone levels are high. GLUT4 is the isulin-regulated glucose transporter found in muscle and adipose tissue. When insulin levels are low the GLUT4 protein is in the ...


3

It's not really possible to break it down this way. The CO2 fixated by the RUBISCO enzyme generates two phosphoglycerate (2 x 3C) molecules from one ribulose bisphophate molecule (5C), while the rest of the Calvin cycle serves to regenerate 3 ribulose bisphophate from 5 phosphoglycerate. Hence, one 3-carbon sugar (glyceraldehyde phosphate or dihydroxyacetone ...


3

I think I understand your question, and stumbled upon it because i was wondering the same thing while studying for my Microbio test. I know its a year late, but someday someone else might need this info...so here it is. To put it simply: there is a second pair of phosphates added to the two 3-carbon molecules cleaved from the preparatory stage before the 4 ...


3

Glucose concentration in the blood is a highly regulated biologic variable. From personal laboratory experience, it is very difficult to raise a healthy, non-diabetic individual's blood glucose over about 6.5-7 mM (i.e. 120-130 mg/dl). My best guess at where the highest glucose concentration might be in the body is within the hepatic portal vein that drains ...


3

The (very) short answer is gluconeogenesis. When glucagon levels are high in response low glucose or low Insulin (perceived in the case of Insulin resistant DM Type II) key enzymes will be inhibited to prevent glycolysis and other enzymes will be activated to produce glucose from various substrates. There are a few sources that can feed into the ...


3

If there is no glucose there is no need for glycolysis: I deduce from this truism that – at some early stage in the evolution of metabolism – a pathway resembling gluconeogenesis must have arisen before glycolysis. This is just another way of stating the obvious fact that autotrophy must have preceded heterotrophy. If the aldolase reaction for triose → ...


3

Your confusion comes entirely from this equation: $\ce{C6H12O6 + 6O2 -> 6CO2 + 6H2O}$ This reaction is the combustion of glucose. This is not how glucose is oxidized in cells! Why so many biology texts and courses present this equation when introducing metabolism is beyond me. Indeed, your tracking of water molecules is correct: starting with one ...


2

Where is this occurring in the body? Almost totally in the liver. To leave the liver as a sugar, it would have had to been converted to glucose, right? Correct, but it's not a direct conversion. Fructose is metabolized almost completely in the liver in humans, and is directed toward replenishment of liver glycogen and triglyceride synthesis... ......


2

The glucose can react with proteins, damaging them. This is called glycation. Note that glucose is the preferred body fuel and has a 10 fold lower ability to cause glycation than fructose. http://en.wikipedia.org/wiki/Glycation


2

Glycogen storage limitation is due to these additional facts also: Glycogen is a hydrophilic molecule. This means an increase in glycogen concentration will cause a proportionate increase cell weight due to water accumulation. As cells can contain only limited volume the amount of glycogen stores are limited. Lipids are hydrophobic hence can be accumulated ...


2

I think this experiment (PDF file) will help you understand the basic concept about the fate of oxygen in aerobic respiration. Basically the result is: The oxygen of respiratory carbon dioxide is in exchange equilibrium with body water. Utilized molecular oxygen is converted to body water. In respect to calculation of electrons donated to oxygen, just ...


2

Actually there is fatty acid transport through the BBB. Maybe the rate of this transport is not enough, I don't know, I think it does not really matter. What really happens here, that the liver prepares the fatty acids, so the brain can use them more easily in the form of ketoacids to produce energy. fatty acid catabolism shared between the liver and the ...


2

Excellent question... "Can you measure plasma glucose with a blood glucose meter?" Absolutely Not! In my experience, if you try to measure plasma glucose with a whole blood glucose meter the results are highly variable for a number of reasons (mentioned below). Using blood glucose meters to measure plasma glucose is dangerous. The meters are calibrated for ...


2

Interpreting your question as "would the Lotka-Volterra predator-prey model be a good model for the glucose-insulin system?" my answer is "no". The predator-prey equations capture assumptions about how prey and predator interact with each other, and how they would fare on their own. These assumptions are not equivalent to any reasonable assumptions about the ...


2

"Is it the phosphate group, or the molecule, that is derived from ATP ?" The Phosphate group is derived from the ATP molecule (thus why Adenosine triphosphate) NOT from the molecule it would be attaching the phosphate group to. Phosphorylation - The process of taking this phosphate group and adding it to another molecule in the energy chain. I hope this ...


2

The reason the monomer units are shown as alternating orientation in the cellulose case and not for starch is due to the angles required for the bonds between the atoms involved. Note that in α-glucose the OH groups of the #1 and #4 carbons are shown on the same side of the ring. When these two groups are changed into a single O joining two α monomers ...


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